<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
{% for order in orders %}
    <p>Заказ #{{ order.id }}</p>
    {% for position in order.positions.all %}
        <p>{{ position.product.name }}: {{ position.quantity }}</p>
    {% endfor %}
{% endfor %}
</body>
</html>